^ox, 7. Environment Agency. Hayling Island North Strategy *. M ^, v. * > -.

Transcription

1 ^ox, 7 Environment Agency Hayling Island North Strategy *. M ^, v. * > -. Consultation Document for Preferred Coastal Defence Options - Septem ber 2005

2 We are the Environment Agency. It s our job to look after your environment and make it a better place - foryou, and for future generations. Your environment is the air you breathe, the water you drink and the ground you walk on. Working with business, Government and society as a whole, we are makingyour environment cleaner and healthier. The Environment Agency. Out there, making your environment a better place. Published by: Catherine Sly Environment Agency Guildbourne House Chatsworth Road Worthing West Sussex BN111LD Tel: enquiries@environment-agency.gov.uk Environment Agency

3 why do we need a strategy for Havline Island North? Hayling Island North is a low-lying residential area. Local people have suffered several floods in recent years. We are reviewing and updating the Hayling Island strategy. Flood risk strategies have already been developed for the south coast of Hayling and Eastoke s northern frontage, and the Selsmore to Mengham frontage. Now we need to do the same for the northern coast of the island to provide a long term plan for coastal defences. We are working with Havant Borough Council s Coastal Team and Hampshire County Council. We will also look to involve you and many others in this process. Strategy Objectives The objectives of the strategy are as follows: Manage the shoreline while protecting the conservation value and status of Chichester and Langstone Harbours; Provide appropriate defences where needed; Provide best value for money; Identify opportunities to improve the environment; Improve and protect the environment. ENVIRONMENT AGENCY Environment Agency Hayling Island North Strategy 3

4 H ayling Island is important for recreation and tourism. The Hayling Billy Coastal Path runs along the western side of the Island. The M ill Rythe Holiday Village has accom modation for 800 people, and Northney Marina provides facilities for boating. The coastal areas are rich in archaeology and the eastern coastal areas are recognised for their beautiful landscapes. The area benefits from a number of important nature conservation designations. These include: The surrounding coastal areas have been designated as SPAs, RAMSARs and SAC. The area supports internationally and nationally important numbers of wintering wildfowl and waders; National nature conservation sites such as the Chichester Site of Special Scientific Interest (SSSIs), with extensive areas of mud and sand flats at low tide. These support large populations of waders and wildfowl. The Langstone Harbour SSSI on the eastern side of the Island has one of the largest areas of mixed saltmarsh found on the south coast of England; There are also a number of local nature conservation designations including the Sandy Point and the West Hayling Local Nature Reserves, and Sites of Nature Conservation Interest (SINCs). 4 Environment Agency Hayling Island North Strategy

5 We carried out an initial review of areas at risk from coastal flooding around Hayling Island. This helped us to determine how likely it was that we would obtain government funding to improve or provide coastal defences. Areas where detailed studies were already underway were not considered. The following areas were selected for more detailed assessment: El: Mill Rythe; F2: Gutner Lane; H: Northney to Langstone Bridge; I, J, K: Langstone Bridge to Stoke Common and L: Newtown. For each area a long list of options was developed and assessed which included: Do Nothing. This option always has to be considered to provide a baseline against which all other options are compared. Do Minimum. Maintain and repair breaches, but the defences will fail at some point. Hold the Existing Line. Improve existing defences. This option will result in loss of saltmarsh and mudflats in the long term. Hold the Existing Line. Improve saltmarsh. This option is not viable. The existing saltmarshes and mudflats around Hayling Island will continue to reduce in size, mainly due to sea level rise. Secondary Line of Defence. Construct defences inland of existing defences. Managed Realignment. Breaching or lowering of the existing line of defences to reduce the impacts of loss of coastline and create new habitats. Environment Agency Hayling Island North Strategy 5

6 and industrial estate are low. Having considered technical, economic and environmental issues the preferred option for this area is to provide a secondary line of defence and road protection which will comprise: - In the first year, we will construct a grassy bank to maintain emergency road access to north-east Hayling during extreme tidal flooding events. - In year 5 we will construct a secondary line of defence. This will involve the construction of an inland bank to protect the majority of residential properties, the schools and the road to maintain emergency road access to north-east Hayling during tidal flooding events. - Until year 10 we will continue to maintain the existing sea defences around Mill Rythe Holiday Village. - Beyond year 10 there is no justification for public investment in maintaining or improvingthe sea defence embankment around the holiday village although these defences may continue to be maintained by the existing land owner. E l: M ill Rythe Three areas are at risk from flooding in Hayling Island North. Mill Rythe Holiday Village; Yacht building yard and industrial estate; and Mill Rythe residential area, including the junior and primary schools and road. The existing sea defence which protects the holiday village is in a reasonable condition, but would need to be raised to provide protection from extreme events. The holiday village is at risk from tidal flooding from both ends as an existing low-level bank between the holiday village and Middle Marsh/Tournerbury Marshes is in very poor condition. The defences in front of the yacht building yard - Between year 20 and 100 it may become too expensive to maintain the defences around Mill Rythe. There is possibility of potential for managed realignment and habitat creation at the holiday village, although the land is low-lying (possibly only suitable for mud-flat creation) and extensive site clearance will be required. - The defences surrounding Mill Rythe yacht building yard and industrial estate are low. They are maintained privately and the area is at risk from flooding almost annually. Due to the limited value of assets at risk from flooding and the length of flood defences which need to be provided, there is no justification for public investment in maintaining or improving flood defences. - In year 20 we will construct a low-level bank to protect the small group of properties in the north-west area from tidal flooding. - In year 50 we will construct a short length of bank, to prevent the road flooding during extreme tidal events and to maintain emergency road access to north-east Hayling. 6 Environment Agency Hayling Island North Strategy

7 Gutner Lane F2: Gutner Lane The existing defences at the front of Chichester Harbour are generally in good condition, although defence levels would need to be raised to provide protection from extreme events. Properties are at risk of tidal flooding from neighbouring areas to the north and south. In addition, flooding occurs in this area as result of an under-sized culvert along the drainage channel which outflows to the harbour to the north of the properties. There is also a lack of flood storage in the rife leading to the outfall. The preferred option for this area is to provide a secondary line of defence and to improve the culvert. The secondary line of defence will comprise of a small inland bank, which will prevent flooding of the road. This will allow emergency access along the road to north-east Hayling during flood events in the short and long term (0 to 100 years). The total value of properties at risk from flooding is not sufficient to justify public investment to provide new defences or improve existing flood defences to protect the properties. Existing property owners will be able to maintain and improve existing flood defence embankments subject to obtaining the necessary approvals. However embankments will need to be maintained to the north and constructed to the south of Gutner Lane to prevent flooding from neighbouring areas. A more economic solution is likely to be for property owners to install flood protection measures to individual properties to provide flood protection against extreme events in the short to medium term (0 to 50 years). Gutner Lane Environment Agency Hayling Island North Strategy 7

8 I, J, K: Langstone Bridge to Newtown I: Langstone Bridge to Stoke Common There are mudflats and saltmarsh in front of the existing low wall. The area behind the defences is rough pasture which is partially flooded by salt water during high tide. There has been some erosion of the existing wall. The section ofthe A3023 highway which approaches Langstone Bridge is low and subject to flooding during extreme flood events. It will become more vulnerable as sea level rises. J: Oyster Beds and Stoke Common The oyster beds have been partially restored to enhance wildfowl habitat. The remaining area ofthe oyster beds is an old landfill site which was closed in the 1960s. The existing flood defences protect the low lying residential area at Stoke. H: Northney to Langstone Bridge Northney The saltmarsh at the western end of Northney Marsh floods on average once a year. The floods prevent access to Northney, Langstone Hotel and the Marina. During extreme floods, this could lead to flooding of properties further inland. The remainder of the existing sea defence banks are generally in good condition, however the eastern section of the bank surrounding Spinnaker Grange needs to be improved and joined into higher ground. Having considered technical, economic and environmental issues the preferred option for this area is to hold the existing line. The preferred option will also improve and close the gap in the existing flood defence embankment to the east of Spinnaker Grange. The marina and hotel are on higher ground and will be responsible for maintenance of defences which surround and protect their assets. K: Stoke Common to Newtown The Hayling Billy coastal path runs along this area and the level of the ground rises to the south. The preferred option for these areas will comprise of: - A secondary line of defence along the northern section. At the north end we will widen the existing beach. We will also carry out minor realignment ofthe footpath inland to the top of the beach and construction of a raised bank which wilt also provide flood protection to the road (A3023) on the southern approach to the bridge and thereafter connecting into locally higher ground to prevent flooding ofthe residential area; - Hold the existing line along the southern section by raising the existing Billy Line embankment/ footpath and possibly redirecting it at the southern end onto higher ground. This option will be developed in consultation with Hampshire County Council; - Measures to protect the approach to Langstone Bridge from flooding in the long term (50 to 100 years). 8 Environment Agency Hayling Island North Strategy

9 Langstone Bridge to Stoke Common L: Newtown A small area of Newtown is potentially at risk from flooding. Low-lying farmland, residential properties and a pumping station are all at risk. This low-lying area is currently protected by a natural shingle beach and a bank. Coastal erosion is a problem in this area and the existing defences could, in the longer term, be outflanked by erosion of the natural coastline on either side. The Hayling Billy line runs parallel with the existing wall and the area between is used for storm water storage. The preferred option for this area will comprise: improving toe protection to reduce the risk of breach and erosion; OR: provision of a secondary line of defence and allowing the existing embankment to fail, which will result in habitat change, with the potential reinstatement of previous inter-tidal habitat. The viability of this option is subject to agreement by environmental bodies on the desirability of habitat change at this inland location which is SPA designated, although the reasoning for the designation is unknown. - EITHER: connecting the existing bank into higher ground to the north and south and Newtown Environment Agency Hayling Island North Strategy 9

10 This map is based upon Ordnance Survey material with the permission of Ordnance Survey on behalf of the Controller of Her Majesty's Stationary Office Crown copyright. Unauthorised reproduction infringes Crown copyright and may lead to prosecution or civil proceedings. Environment Agency. Licence number Environment Agency Hayling Island North Strategy

11 Have your say The preferred options have been developed and assessed in line with government guidelines. We want to know what you think. Your opinions on the preferred options are important: Do you support the preferred options? Do you have ideas for improvements? Do you have any other comments? Please let us have your comments Environment Agency, Hampshire and Isle of W ight Area, Colvedene Court, Wessex Business Park, Wessex Way, Colden Common, Winchester, Hampshire,S0211WP. bret.davies@environment-agency.gov.uk What happens next? We will incorporate any comments that we receive in the Strategy Report, which will define the construction, improvement or maintenance works that are required to improve coastal defences around Hayling Island North in the next five years and an overall plan for the next 100 years. The strategy will then be issued to the Department for the Environment, Food and Rural Affairs (Defra) for review and approval. Project Appraisal Reports for some of the schemes will be produced in Subject to Defra approval, detailed design will be undertaken in 2007, followed by construction of new coastal defences in 2007/ 2008.

12 Would you like to find out more about us or about your environment? Then call us on (Mon-Fri 8-6) or visit our website incident hotline (24hrs) floodline Environment first: This publication is printed on paper made from 100 per cent previously used waste. By-products from making the pulp and paper are used for composting and fertiliser, for making cement and for generating energy. GESO0805BJOY-E-P